Guy I'm hooking up a Harman vf3000 in series with my gas boiler. I need to wire up the dump zone, and have a question about the wiring.

Question: Can you wire one appliances with two separate 110 volts feeds? what if they both go on at the same time? still feeding 110 volts. Do I just need to be sure I have the neutrals wired together. It's not going to make 220 volts right?

I have a 110 VAC feed from the Harman that will run the existing circ pump and open a zone valve through a 24 volt transformer when it needs to dump heat.

I asked a life-long electrician about that one time because of a well-pump issue with two houses using the same pump. He said it was OK. I think I also have the same situation with my current boiler and the backup boiler.

I think the safety issue will be that if there's a problem, that the electrical load is definitely protected by a breaker(s).

Coalbrokdale wrote:Guy I'm hooking up a Harman vf3000 in series with my gas boiler. I need to wire up the dump zone, and have a question about the wiring.

Question: Can you wire one appliances with two separate 110 volts feeds? what if they both go on at the same time? still feeding 110 volts. Do I just need to be sure I have the neutrals wired together. It's not going to make 220 volts right?

I have a 110 VAC feed from the Harman that will run the existing circ pump and open a zone valve through a 24 volt transformer when it needs to dump heat.

Is there an easier way to wire this?

No, don't ever have two direct feeds from different circuits in one or more circuit breaker panels. Provide power to the pump from a single circuit protected feed. Control that power with one or more relays. The relay coils can be powered from different circuits. It's the relay that gives you circuit isolation. There are safety issues with what you propose.

A very simple dump zone may be accomplished using a Honeywell of equivalent close on temperature rise (strap on or temperature well) aqua stat - and having it close one or several thermostat circuits - thus calling for heat to be sent to the load until the overrun is scrubbed off. Set to close five to ten degrees above your current hi limit (mine is set to close and launch the dump sequence at 205 and quiets when vessel temp again falls back to 190)

No need for anything extra if only launching one good sized zone - but if you wish for more "dump" load use a simple DPST ice cube relay powered by the low voltage of the t-stat circuit and closed by the Honeywell. There - all done - no "dangerous" voltage involved - and the heat was scrubbed into an area where (possibly) it will not be wasted.

I'm an electrician. If you bring two hot wires to the same device you will get one of two results. If both "hot" wires originate from the "A" phase or the "B" phase then you will get only 110 v from either wire to neutral, and you will get 0 volts between the two hot legs. There is no difference of potential between two wires from the same phase. There is a difference of potential between N and H though. Why do this when one hot will do? If you bring two hot phases to the device and ONE is from "A" phase and ONE is from "B" phase you WILL get 220V between the hot wires and 110V from any hot wire to neutral. If you need 220 this is fine. If you don't, this could be a very destructive process for your equipment and possibly very dangerous to your health and surrounding property. It sounds like you should find a qualified electrician to assist you. The electrician can make sense of your electrical requirements and resources. I know people don't like to pay a lot for electrical work but miss-wiring causes a lot of electrical fires. You have to sleep here, it's better if it's safe. Best Wishes......Paul

My two boilers are separated by 50 feet, so I took 110V from the garage to supply voltage to my garage boiler and used a relay to send 24V to the other boiler's circulator relay, which is powered by 110V from the main panel. Either I'm lucky, or the relays protect the two sources of 110V from each other.

I had a scary experience with the wiring for my well pump. My neighbor and I share the same well, so we both had 220V going to the well pit. We were supposed to have one of us supply 220V for a year and then switch. Well, one day, I wanted to shut off the power to the entire house, so I pulled the main breaker and the lights stayed on. Then I realized that we both had our breakers turned on in the well pump at the same time. And who knows how long that was the case; for at least a year or more. Now we just have one plug out in the pit and each of us has a separate receptacle, so that can't happen again. Well, actually, he hasn't installed his receptacle, so I've been paying the whole bill for at least 10 years.

stoker-man wrote:I had a scary experience with the wiring for my well pump. My neighbor and I share the same well, so we both had 220V going to the well pit. We were supposed to have one of us supply 220V for a year and then switch. Well, one day, I wanted to shut off the power to the entire house, so I pulled the main breaker and the lights stayed on. Then I realized that we both had our breakers turned on in the well pump at the same time. And who knows how long that was the case; for at least a year or more. Now we just have one plug out in the pit and each of us has a separate receptacle, so that can't happen again. Well, actually, he hasn't installed his receptacle, so I've been paying the whole bill for at least 10 years.

The fair way to share the electric costs would be to have a relay that switches the source of power, yours then the neighbors each time the pump runs. Like an industrial setup for sharing two air compressors, one runs then the other. Sometimes both run when there is a large demand. Of course that doesn't apply to your well pump. Or maybe if you apply 440 the pump would run twice as fast.

Why didn't you shut off your main breaker and let your neighbor power your house for a awhile?

That's a quick way to recoup your costs!!

stoker-man wrote:I had a scary experience with the wiring for my well pump. My neighbor and I share the same well, so we both had 220V going to the well pit. We were supposed to have one of us supply 220V for a year and then switch. Well, one day, I wanted to shut off the power to the entire house, so I pulled the main breaker and the lights stayed on. Then I realized that we both had our breakers turned on in the well pump at the same time. And who knows how long that was the case; for at least a year or more. Now we just have one plug out in the pit and each of us has a separate receptacle, so that can't happen again. Well, actually, he hasn't installed his receptacle, so I've been paying the whole bill for at least 10 years.

Hey Thanks again for all the input.... Yeah I figured it out, I'm just going to tap the power from the Gas boiler and power the Harmans' Johnson Controls. This way I'm positive which circit and phase i"m using. Just keep the Hot an Neutrals the same. I still havent found a solution to trip the Zone valve with 24 volts other then powering a seperate transformer with the same 110 VAC and matching DC volts, which I'm much more farmiliar with. I then just need to be sure of the polarity so I maintain 24 volts even if both feed are live. A Voltage meter will show me that..

On Monday, I can find out a better explanation to operate your zone valve. With the efm wood boiler, the dump zone was created this way:

A V8043 zone valve was used. There are 4 terminals from left to right. They were, in sequence, TH, TR, TH, TR. and two terminals at the top for T and T from the gas boiler. All wiring is 24V. I'll call the 4 terminals as 1,2,3, and 4.

T and T wires from the gas boiler were hooked to the two TT terminals in the V8043 zone valve. On term. 1, was hooked a wire from one side of the tstat. A wire also hooked to #1 ran to a B aquastat, either an L4006B or L6006B and hooked to one of the terminals. On the other terminal of the B aquastat was hooked a wire, which ran to #3. The other wire from the tstat also hooks to #3. One wire from a transformer hooks to #2 and the other wire from the transformer hooks to #4. It doesn't matter which wire you use from the transformer, tstat, or B aquastat as long as they hook up right at the zone valve.

This is not the method I used. I have a B aquastat (which closes on temperature rise) mounted into the boiler. When the temp rises, low voltate travels from the transformer to my Taco zone valve, top terminal, and simulates a call for heat from my tstat.

Actually it turns out that just feeding the zone valve the 24volts trips the relay and activates the circ pump... So I don't need to wire the circ pump. Can't talk now I'm watching the boiler like a TV. Wife keep says why are you still down there... Ha this thing is sweet!